1. Field of the Invention
The present invention relates to a liquid ejecting head and a method for producing the same.
2. Description of the Related Art
An ink jet recording head for ink jet printing generally includes an ejection port for ejecting a solution, a liquid flow channel in communication with the ejection port, and an ejection energy generating element provided in the liquid flow channel. This ink jet recording head is broadly divided into two forms, from the viewpoint of a positional relationship between the ejection energy generating element and the ejection port. In the two forms, one is an edge shooter type ink jet head in which a growth direction of an air bubble is different from an ejection direction thereof (almost vertical), and the other is a side shooter type ink jet head in which the growth direction of the air bubble is almost same as the ejection direction thereof.
The side shooter type ink jet head can be produced, for instance, according to the following steps (1) to (4): (1) a step of forming a mold pattern of the ink flow channel on a substrate (base substance) having the ejection energy generating element formed thereon by using a dissolvable resin; (2) a step of forming a flow-channel forming member which constitutes a wall of the ink flow channel, by solvent-coating a coating resin containing an epoxy resin on the mold pattern; (3) a step of forming the ink ejection port in a coating resin layer which exists above the ejection energy generating element; and (4) a step of dissolving out the mold pattern which is formed of a dissolvable resin.
The above described production method will be described in detail below with reference to FIGS. 1A to 1E.
First, as is illustrated in FIG. 1A, the mold pattern 23 of the ink flow channel is formed on the substrate 21 which has the ejection energy generating element 22 formed on its first face (which is also referred to as surface), with the use of the dissolvable resin.
Here, a desired number of the ejection energy generating elements 22 such as an electrothermal conversion element, a piezoelectric element or the like are arranged on the substrate 21. An energy for ejecting an ink small drop as a recording liquid is given to the ink by the ejection energy generating element 22.
When the electrothermal conversion element is used as the ejection energy generating element 22, the electrothermal conversion element heats the recording liquid in the vicinity thereof, thereby causes the change in a state of the recording liquid, and generates ejection energy. In addition, when the piezoelectric element is used as the ejection energy generating element 22, the ejection energy is generated by mechanical vibration of the piezoelectric element.
Subsequently, as in FIG. 1B, the coating resin layer 24 having photosensitivity is further formed on the mold pattern 23 which serves as a mold of the ink flow channel, with a spin coating method, a roll coating method or the like.
Subsequently, as in FIG. 1C, the ejection port 25 is formed by the exposure of the coating resin layer 24 to light through a mask having the pattern and the development of the exposed coating resin layer.
A negative type resist, for instance, can be used for the photosensitive coating resin layer 24. When the coating resin layer 24 is the negative type resist, a portion (not-shown) on which the ejection port is formed and a portion (not-shown) for electrical connection thereon are shielded by a mask.
A light source to be used for the pattern exposure can be appropriately selected from ultraviolet light, Deep-UV light, an electron beam, X-rays or the like, according to a photosensitizing region of a cationic photopolymerization initiator to be used.
Subsequently, as is illustrated in FIG. 1D, an ink supply port 27 for supplying the ink to the ink flow channel therethrough is formed. At this time, in order to avoid a damage to the coating resin layer 24 which serves as a nozzle member, a face of the silicon substrate on which the nozzle has been formed may be protected by a protective material 26 such as a cyclized rubber. In addition, the protective layer may be removed after the ink supply port 27 has been formed.
In addition, the ink supply port can be formed with any method as long as a through hole can be formed in the substrate 21. The ink supply port may be formed, for instance, mechanically with a drill or the like, or may also be formed with the use of light energy of a laser or the like. In addition, the through hole may be formed by steps of forming a resist pattern on the substrate 21 and chemically etching the substrate.
Subsequently, as is illustrated in FIG. 1E, the mold pattern 23 formed of the dissolvable resin is dissolved out by a solvent, and the ink flow channel is formed.
The mold pattern 23 is easily dissolved out by immersing the substrate in the solvent or spraying the solvent to the substrate with a spray. In addition, if an ultrasonic wave or the like has been used together, a dissolving period of time can be further shortened.
With the substrate 21 having the ink flow channel and the ink ejection port formed thereon in this way, members for supplying the ink are attached and electrical connections (not-shown) for driving the ejection energy generating element 22 are provided to complete the ink jet recording head.
Japanese Patent Application Laid-Open No. H05-116317 discloses a liquid ejecting head that has a structure which has an orifice opposing to a thermal energy supply unit, and has nozzle walls arranged in two different directions from each other when viewed from the thermal energy generating unit, in the vicinity of the thermal energy generating unit.
In addition, U.S. Pat. No. 6,534,247 describes a method for forming a liquid ejecting head according to the following steps of: (1) arranging an inorganic insulation film on the upper face and the lower face of a heater layer, and forming an independent supply port (Ink Feed) in the vicinity of a heater first from the surface of a substrate for an ink jet recording head; (2) forming a first common ink supply port by anisotropic etching from the rear face of the substrate for the recording head, with the use of a strong alkaline etchant; and (3) applying a resist onto the substrate with a spray coater or the like to form the film, patterning the resist film, and then forming a second common ink supply port to make the second common ink supply port communicate with the above described independent supply port. In U.S. Pat. No. 6,534,247, the independent supply port is formed from the surface of the substrate for the ink jet recording head, and accordingly such a step is not needed as to remove an inorganic insulation film arranged on the upper face and the lower face of the heater layer, from the rear face of the substrate through the independent supply port. However, it is difficult to stack nozzles on the above described substrate for the ink jet recording head with high accuracy, after deep independent supply ports have been formed on the surface. In addition, a material for temporarily plugging the above described independent supply ports also becomes necessary, and a process of uniformly plugging this plugging material also becomes complicated. Furthermore, it is needed to stably remove the above described plugging material at the end in order to form the nozzles.
In addition, Japanese Patent Application Laid-Open No. 2006-150744 discloses the following method of producing an ink jet recording head. Specifically, the method includes arranging a TaSiN film which is a heater film, between a P—SiO film and a P—SiN film in a region in which a common ink supply port is formed, in an ink jet recording head disclosed in Japanese Patent Application Laid-Open No. H06-286149, and anisotropically etching the region. Then, when the P—SiO film is removed by a solution having acidity such as a BHF solution, the method prevents a damage to the above described dissolvable resin material layer 23, the above described photosensitive coating resin layer 24 and the like, through the P—SiN film.
In addition, Japanese Patent Application Laid-Open No. 2009-039914 and Japanese Patent Application Laid-Open No. 2009-196244 disclose a structure that specifies a nozzle arrangement configuration of the recording head, which achieves such a symmetrical nozzle configuration that the nozzles are filled with ink through independent supply ports in a head having the independent supply ports, and specifies an arrangement configuration of the independent supply ports.